Paved surfaces such as roads and parking lots are commonly constructed with a top surface layer of asphalt or concrete paving material. Over a period of time, the paved surface usually deteriorates due to the effects of traffic, temperature cycles, and other environmental causes. Cracks develop in the paved surface, and the cracks can spread and cause further deterioration. Water can penetrate the paved surface by flowing into the cracks, causing further damage.
Damaged paved surfaces are usually repaired by applying a new surface layer of paving material over the damaged portions or over the entire paved surface. After a paved surface having cracks is resurfaced, many times the new surface layer cracks directly over the cracks in the old surface, an occurrence known as “reflective cracking.” One way to address this problem is to make the new surface layer thicker, but this is not very effective.
Consequently, various materials have been tried for waterproofing and for preventing or repairing cracks and other deterioration in paved surfaces. Some commercial products are needle-punched non-woven mats or geotextile fabrics constructed from polypropylene fibers. The product is applied over a hot tack coat of asphalt, and then a surface layer of hot asphalt paving material is applied over the mat. Unfortunately, the products made with polypropylene fibers tend to shrink, stretch and/or melt when they are exposed to the hot tack coat and/or hot paving material, which detracts from their effectiveness.
Another commercial product is the TruPave® Paving Mat developed by Owens Corning. This product is a non-woven mat constructed from a mixture of glass and polyester fibers. Compared with the polypropylene products, this product is more resistant to shrinking, stretching and melting, and it has improved strength.
Some patents describe different types of fibrous mats. For example, U.S. Pat. No. 4,359,546 discloses a non-woven paving mat made from a mixture of glass fibers and polymer fibers. Preferably, the glass fibers are from 6.35 mm to 50.8 mm in length and comprise about 60 to 80 percent by weight of the mat fibers. The polymer fibers are preferably from 25 mm to 40 mm in length and comprise up to about 40 percent of the mat fibers. The mat is made with a binder that includes from 91% to 97% aqueous thermoplastic emulsion, from 3% to 7% melamine formaldehyde resin and up to 2% water-soluble ammonium salt catalyst.
U.S. Pat. No. 6,737,369 discloses a non-woven roofing mat made from glass fibers, polymer fibers, or mixtures thereof. A majority of the fibers present in the mat are preferably unmixed glass fibers. The mat fibers have different fiber lengths. Specifically, the mat comprises a mixture of fibers where from 0 to 100 percent of the fibers have a median length of from 0.5 mm to 60 mm, and from 0 to 100 percent of the fibers have a median length of from 10 mm to 150 mm. The mat is made with any conventional binder, such as acrylamide, starch, urea resin, phenol resin, sodium silicate, epoxy resin, styrene-butadiene rubber, acryic, neoprene or acrylonitrile.
U.S. Patent Application Publication No. 2005/0136241 discloses a non-woven fibrous mat coated with foam for use as an exterior wallboard facing. Preferably, the majority of the fibers are glass fibers, but polymer fibers can be mixed with the glass fibers. The fibers are at least 6 mm long, and mixtures of different length fibers can be used. The binder used to bond the fibers together can include urea formaldehyde modified with acrylic.
U.S. Pat. No. 6,586,353 discloses a roofing mat made from glass fibers, polymer fibers or mixtures thereof. In a preferred embodiment, the mat is made from glass fibers bonded together by a binder comprising 75% to 99% urea formaldehyde and 1% to 25% acrylic latex.
U.S. Pat. No. 6,630,046 discloses a wall or floor fiberglass containing mat wherein up to 40% of the glass fibers can be substituted by other fibers, including polymer fibers. The binder for the mat can include acrylic or urea formaldehyde.
In view of the above, it would be desirable to provide a further improved paving mat for use in paved surfaces.